While she did not blame the government for the attack, she suggested an inquiry into why street lights on the route of the convoy were not working should be conducted.

Bhutto blamed the attacks on supporters of Islamist groups such as Al-Qaeda and the Taliban.

"If it means sacrificing our lives, then we are prepared to risk our lives, but we are not prepared to surrender our great nation to the militants," said Bhutto, wearing a black armband in memory of the victims.

Kamal Hyder, Al Jazeera's correspondent in Islamabad, said pro-Taliban groups had denied they were involved.

The attacks are the deadliest bombings ever to have taken place in

"There was blood and gore all over our clothes. The street was littered with dead bodies, and blood and glass," she said.

Conflicting claims

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"Perhaps Bhutto should have listened to Musharraf and delayed her return to Pakistan until the volatile security situation was better"

Pervez Musharraf, Pakistan's military ruler called Bhutto to "convey his deepest sorrow over the terrorist attack" and pledged to arrest the culprits, said retired Major General Rashid Qureshi, a presidential spokesman.

Bhutto had earlier accused supporters of late military ruler Muhammad Zia ul-Haq of being behind the blasts, in an interview published in French on the Internet site of Paris Match magazine.

Zia overthrew Bhutto's father, prime minister Zulfikar Ali Bhutto, in 1977 and had him hanged two years later.

Bhutto had returned to Pakistan after eight years in voluntary exile as part of a power sharing deal with Musharraf, the general who seized power in a 1999 coup.

Bombing confusion

The former prime minister could lead her Pakistan People's Party in elections due to take place in January next year.

Kamal Hyder said on Friday: "The bomb disposal unit is saying these were planted devices. However, security aides who were close to Benazir say this was a suicide attack.

"Whoever carried out the attack, planned it very well. The attack is a signal of how violent Pakistan has become.

"Now the political parties are being lumped into religious or secular parties and that is a very dangerous divide for a place like Pakistan

Bhutto described hearing the blasts while sat inside the truck working on a speech she was to deliver to a rally.

"We know shots were fired and these were fired towards the truck."

She said shots were fired to stop the truck or to kill bystanders, and that a man armed with a pistol had been caught.